AT2022sxl: A Candidate Repeating Tidal Disruption Event in Possible Association with Two High-Energy Neutrino Events

TL;DR

This paper reports a candidate repeating tidal disruption event, AT2022sxl, possibly associated with two high-energy neutrino events, highlighting the potential link between luminous MIR emission in TDEs and neutrino production.

Contribution

It presents the discovery of a repeating TDE with multi-wavelength observations and suggests a possible connection between MIR luminosity and neutrino emission in TDEs.

Findings

Two optical flares separated by 7.2 years observed.

Mid-infrared flares delayed by about 200 days detected.

Two IceCube neutrino events spatially and temporally match the TDE.

Abstract

We report a candidate repeating tidal disruption event (TDE), AT2022sxl, found from large-field optical survey data. Two flares with a separation time of $\sim$7.2\,yr between the two optical peaks are observed. Related mid-infrared (MIR) flares, with delay times of $\sim$200\,day are also seen. We analyze two optical spectra of the TDE source, onenear the optical peak of the second flare from the Transient Name Server and one at the quiescent flux level after the second flare. The latter was taken by us with the 10.4-m Gran Telescopio Canarias. Comparing the features of the two spectra, we identify that the host is likely a composite galaxy at redshift 0.23 and the TDE event, probably an H+He type, mainly powered broad components in the emission lines of H$\alpha$, H$\beta$, and He~I $\lambda$5876. More interestingly, we find that two Bronze-type neutrino events, detected by the IceCube neutrino observatory, match the TDE in position and the second flare, especially the delayed MIR flare, in time. We discuss the MIR luminosity properties of the currently reported (candidate) neutrino-emitting TDEs and suggest that luminous MIR emission is a prerequisite for neutrino production in TDEs.